Simrad PSIMH1 datagram format
Simrad PSIMH1 is a proprietary datagram format created by Kongsberg Discovery to provide the height between the headrope and the footrope (opening), and the height between the headrope and the bottom. It also provides the horizontal distance and the slant range between the vessel and the sensor, as well as the true bearing. These values are used together with the GPS position of the vessel to calculate the position of the sensor.
Format
$PSIMH2,xx,M,yy,M,z.z,T,g.g,M,i.i,M,hhmmss*hh<CR><LF>
Description
1 $PSIMH1Talker identifier
2 xx,MSlant Range to sensor (metres)
3 yy,MHorizontal range to sensor (metres)
4 z.z,TTrue Bearing (metres)
5 g.g,MOpening (to footrope)  (metres)
6 i.i,MHeight (to bottom) (metres)
7 hhmmssTime of transmission
8 *hhChecksum
Note
If your trawl system has two height sensors, the information of the sensor sensor is provided in the Simrad PSIMH2 datagram.